1. Field of the Invention
The present invention relates to the preparation or purification of organic chemicals, and particularly to compounds which are to be added to photothermographic compositions and elements.
2. Background of the Art
Standard purification methods for chemical compounds, including those used in photothermographic elements comprise such conventional treatments as solvent extraction, recrystallization, chromotography, vacuum distillation, and other well known physical and chemical treatments. These procedures are useful with the purification of many different compounds, but have been found to be particularly ineffective in the purification of certain active agents for use in photothermography, where the presence of strong silver reducing agents is particularly damaging to the composition.
Silver oxide or silver nitrate on silica gel or alumina are well known in standard chemical procedures as agents which oxidized (by chemical reaction) to remove certain organic compounds. These are also used as reagents in organic synthetic procedures.